This invention relates generally to manufacturing production systems, and more particularly, the present invention relates to a method, system, and storage medium for resolving transport errors relating to Automated Material Handling System (AMHS) transactions between a Manufacturing Execution System (MES) and a Material Control System (MCS).
The efficiency of a manufacturing enterprise depends, in part, on the quick flow of information across its complete supply chain. Off-the-shelf enterprise resource planning (ERP) systems were developed and utilized for handling product planning, purchasing, supplier interactions, and customer service and soon gained widespread acceptance. Though useful, these ERP systems were not designed to manage the day-to-day plant-floor operations. Historically, it has been common practice for manufacturers to purchase commercially available MES's or build their own plant-floor control systems. For example, most semiconductor manufacturers, or fabricators (also referred to as ‘FABs’) purchase commercially available MES's or use some form of ‘home-grown’ manufacturing execution system (MES) for tracking production logistics, work-in-process (WIP), equipment status, quality, inventory, process controls, etc.
More recent advancements in shop-floor activities include the automation of production equipment, material processing, material control systems, and the integration of all these systems and applications with the host MES. Automating manufacturing processes for certain industries present many challenges. Unlike the automotive industry which employs standard assembly-line processing techniques, the manufacture of semiconductor materials generally involves non-linear processing techniques. For example, a 300-mm semiconductor FAB involves a complex and lengthy back-and-forth route in which wafers revisit numerous repetitive levels back through process tools while measurements and feedback of measurements are taken. Automating such complex routes requires a great deal of sophistication in its underlying technology. Another challenge involves the logistics of size and weight of semiconductor materials. For example, the development of 300-mm wafers which are substantially larger and heavier than their 200-mm predecessors led to multi-floor FABs necessary to accommodate these space-consuming materials. Increased automation in this regard becomes more critical in order to reduce the higher risk of injuries likely to occur with human handling and to overcome regulatory restrictions placed by various agencies.
Automated Material Handling Systems (AMHSs) were developed to move and track material carriers (also referred to as FOUPs or Front Opening Unified Pods and reticle pods) that are routed through a manufacturing facility or bay. These carriers can also be reduced pitch FOUPs, or any other type of wafer carrier, reticle carrier, or durable used in the manufacture of semiconductors. AMHS subsystems include stockers (also referred to as material storage and retrieval systems), interbay transport devices, and intrabay transport devices. Interbay transport devices move carriers from one stocker to another as well as between bays. Intrabay transport allows movement of a carrier directly to the production equipment either from a stocker or from another production equipment in the bay. Automated interbay and intrabay transport vehicles are often referred to as automatic guided vehicles (AGVs), rail guided vehicles (RGVs), or any type of overhead transport/overhead hoist transport (OHT), and overhead vehicles (OHVs). Software used for implementing AMHS activities include material control system (MCS) software. MCS software manages the automation of transportation and storage of manufacturing materials.
While stockers and interbay transport have been around for some time, automated intrabay transport is fairly new. Integrating MCS systems into the MES system is necessary to enable automated delivery and pickup, as well as automated material processing. The relative newness of intrabay transport has led to gaps in the integration of MCS with MES.
The MCS or AMHS begins the automated delivery process, but occasionally a hardware, software or human error causes the E84 handshake (a series of infrared parallel I/O signals that allows direct communication from the active AMHS vehicle or entity with the passive production equipment entity) to fail. The MCS control system will then send a message to the MES stating that the transport job was completed to an alternate location.
The MES (which receives commands back from the MCS) does not interrogate these return codes and errors but continues on operating and processing as if the error never occurred. The MES does not acknowledge the return codes or messages from the MCS message, and assumes the carrier has been delivered successfully. As a result, it also assumes that the processing instructions, as defined via the control job/process job, are being carried out. This has been confirmed by recreating this exact scenario in a test environment and documenting how all the systems interact and react to this error. The MES assumes that the reserved carrier was successfully delivered even though the associated control job, process job, and the materials defined have not been processed. The MCS sends the carrier back to the MCS stocker of its choice (often the nearest), but the carrier reservation and control job reserved for the equipment load port are not canceled by the MES.
This problem is generally caused by one of the following reasons: an E84 failure by the equipment or MCS AMHS vehicle; an operator error such as a manual delivery to the wrong load port or the wrong tool used so the load port is incorrectly occupied; a human error such as an interference with presence and placement sensors, leaving tools on the load port, or leaning on the load port; and a carrier presence and/or placement errors. Any of these events can result in substantial increases in costs as well as long delays in the manufacturing cycle.
What is needed is an efficient way to identify, track, and resolve transport failures occurring in an automated manufacturing setting.